btree.c

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/*
 *  linux/fs/hfsplus/btree.c
 *
 * Copyright (C) 2001
 * Brad Boyer ([email protected])
 * (C) 2003 Ardis Technologies <[email protected]>
 *
 * Handle opening/closing btree
 */

#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/log2.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"


/* Get a reference to a B*Tree and do some initial checks */
struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id)
{
    struct hfs_btree *tree;
    struct hfs_btree_header_rec *head;
    struct address_space *mapping;
    struct inode *inode;
    struct page *page;
    unsigned int size;

    tree = kzalloc(sizeof(*tree), GFP_KERNEL);
    if (!tree)
        return NULL;

    mutex_init(&tree->tree_lock);
    spin_lock_init(&tree->hash_lock);
    tree->sb = sb;
    tree->cnid = id;
    inode = hfsplus_iget(sb, id);
    if (IS_ERR(inode))
        goto free_tree;
    tree->inode = inode;

    if (!HFSPLUS_I(tree->inode)->first_blocks) {
        printk(KERN_ERR
               "hfs: invalid btree extent records (0 size).\n");
        goto free_inode;
    }

    mapping = tree->inode->i_mapping;
    page = read_mapping_page(mapping, 0, NULL);
    if (IS_ERR(page))
        goto free_inode;

    /* Load the header */
    head = (struct hfs_btree_header_rec *)(kmap(page) +
        sizeof(struct hfs_bnode_desc));
    tree->root = be32_to_cpu(head->root);
    tree->leaf_count = be32_to_cpu(head->leaf_count);
    tree->leaf_head = be32_to_cpu(head->leaf_head);
    tree->leaf_tail = be32_to_cpu(head->leaf_tail);
    tree->node_count = be32_to_cpu(head->node_count);
    tree->free_nodes = be32_to_cpu(head->free_nodes);
    tree->attributes = be32_to_cpu(head->attributes);
    tree->node_size = be16_to_cpu(head->node_size);
    tree->max_key_len = be16_to_cpu(head->max_key_len);
    tree->depth = be16_to_cpu(head->depth);

    /* Verify the tree and set the correct compare function */
    switch (id) {
    case HFSPLUS_EXT_CNID:
        if (tree->max_key_len != HFSPLUS_EXT_KEYLEN - sizeof(u16)) {
            printk(KERN_ERR "hfs: invalid extent max_key_len %d\n",
                tree->max_key_len);
            goto fail_page;
        }
        if (tree->attributes & HFS_TREE_VARIDXKEYS) {
            printk(KERN_ERR "hfs: invalid extent btree flag\n");
            goto fail_page;
        }

        tree->keycmp = hfsplus_ext_cmp_key;
        break;
    case HFSPLUS_CAT_CNID:
        if (tree->max_key_len != HFSPLUS_CAT_KEYLEN - sizeof(u16)) {
            printk(KERN_ERR "hfs: invalid catalog max_key_len %d\n",
                tree->max_key_len);
            goto fail_page;
        }
        if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
            printk(KERN_ERR "hfs: invalid catalog btree flag\n");
            goto fail_page;
        }

        if (test_bit(HFSPLUS_SB_HFSX, &HFSPLUS_SB(sb)->flags) &&
            (head->key_type == HFSPLUS_KEY_BINARY))
            tree->keycmp = hfsplus_cat_bin_cmp_key;
        else {
            tree->keycmp = hfsplus_cat_case_cmp_key;
            set_bit(HFSPLUS_SB_CASEFOLD, &HFSPLUS_SB(sb)->flags);
        }
        break;
    default:
        printk(KERN_ERR "hfs: unknown B*Tree requested\n");
        goto fail_page;
    }

    if (!(tree->attributes & HFS_TREE_BIGKEYS)) {
        printk(KERN_ERR "hfs: invalid btree flag\n");
        goto fail_page;
    }

    size = tree->node_size;
    if (!is_power_of_2(size))
        goto fail_page;
    if (!tree->node_count)
        goto fail_page;

    tree->node_size_shift = ffs(size) - 1;

    tree->pages_per_bnode =
        (tree->node_size + PAGE_CACHE_SIZE - 1) >>
        PAGE_CACHE_SHIFT;

    kunmap(page);
    page_cache_release(page);
    return tree;

 fail_page:
    page_cache_release(page);
 free_inode:
    tree->inode->i_mapping->a_ops = &hfsplus_aops;
    iput(tree->inode);
 free_tree:
    kfree(tree);
    return NULL;
}

/* Release resources used by a btree */
void hfs_btree_close(struct hfs_btree *tree)
{
    struct hfs_bnode *node;
    int i;

    if (!tree)
        return;

    for (i = 0; i < NODE_HASH_SIZE; i++) {
        while ((node = tree->node_hash[i])) {
            tree->node_hash[i] = node->next_hash;
            if (atomic_read(&node->refcnt))
                printk(KERN_CRIT "hfs: node %d:%d "
                        "still has %d user(s)!\n",
                    node->tree->cnid, node->this,
                    atomic_read(&node->refcnt));
            hfs_bnode_free(node);
            tree->node_hash_cnt--;
        }
    }
    iput(tree->inode);
    kfree(tree);
}

void hfs_btree_write(struct hfs_btree *tree)
{
    struct hfs_btree_header_rec *head;
    struct hfs_bnode *node;
    struct page *page;

    node = hfs_bnode_find(tree, 0);
    if (IS_ERR(node))
        /* panic? */
        return;
    /* Load the header */
    page = node->page[0];
    head = (struct hfs_btree_header_rec *)(kmap(page) +
        sizeof(struct hfs_bnode_desc));

    head->root = cpu_to_be32(tree->root);
    head->leaf_count = cpu_to_be32(tree->leaf_count);
    head->leaf_head = cpu_to_be32(tree->leaf_head);
    head->leaf_tail = cpu_to_be32(tree->leaf_tail);
    head->node_count = cpu_to_be32(tree->node_count);
    head->free_nodes = cpu_to_be32(tree->free_nodes);
    head->attributes = cpu_to_be32(tree->attributes);
    head->depth = cpu_to_be16(tree->depth);

    kunmap(page);
    set_page_dirty(page);
    hfs_bnode_put(node);
}

static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
{
    struct hfs_btree *tree = prev->tree;
    struct hfs_bnode *node;
    struct hfs_bnode_desc desc;
    __be32 cnid;

    node = hfs_bnode_create(tree, idx);
    if (IS_ERR(node))
        return node;

    tree->free_nodes--;
    prev->next = idx;
    cnid = cpu_to_be32(idx);
    hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);

    node->type = HFS_NODE_MAP;
    node->num_recs = 1;
    hfs_bnode_clear(node, 0, tree->node_size);
    desc.next = 0;
    desc.prev = 0;
    desc.type = HFS_NODE_MAP;
    desc.height = 0;
    desc.num_recs = cpu_to_be16(1);
    desc.reserved = 0;
    hfs_bnode_write(node, &desc, 0, sizeof(desc));
    hfs_bnode_write_u16(node, 14, 0x8000);
    hfs_bnode_write_u16(node, tree->node_size - 2, 14);
    hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);

    return node;
}

struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
{
    struct hfs_bnode *node, *next_node;
    struct page **pagep;
    u32 nidx, idx;
    unsigned off;
    u16 off16;
    u16 len;
    u8 *data, byte, m;
    int i;

    while (!tree->free_nodes) {
        struct inode *inode = tree->inode;
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        u32 count;
        int res;

        res = hfsplus_file_extend(inode);
        if (res)
            return ERR_PTR(res);
        hip->phys_size = inode->i_size =
            (loff_t)hip->alloc_blocks <<
                HFSPLUS_SB(tree->sb)->alloc_blksz_shift;
        hip->fs_blocks =
            hip->alloc_blocks << HFSPLUS_SB(tree->sb)->fs_shift;
        inode_set_bytes(inode, inode->i_size);
        count = inode->i_size >> tree->node_size_shift;
        tree->free_nodes = count - tree->node_count;
        tree->node_count = count;
    }

    nidx = 0;
    node = hfs_bnode_find(tree, nidx);
    if (IS_ERR(node))
        return node;
    len = hfs_brec_lenoff(node, 2, &off16);
    off = off16;

    off += node->page_offset;
    pagep = node->page + (off >> PAGE_CACHE_SHIFT);
    data = kmap(*pagep);
    off &= ~PAGE_CACHE_MASK;
    idx = 0;

    for (;;) {
        while (len) {
            byte = data[off];
            if (byte != 0xff) {
                for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
                    if (!(byte & m)) {
                        idx += i;
                        data[off] |= m;
                        set_page_dirty(*pagep);
                        kunmap(*pagep);
                        tree->free_nodes--;
                        mark_inode_dirty(tree->inode);
                        hfs_bnode_put(node);
                        return hfs_bnode_create(tree,
                            idx);
                    }
                }
            }
            if (++off >= PAGE_CACHE_SIZE) {
                kunmap(*pagep);
                data = kmap(*++pagep);
                off = 0;
            }
            idx += 8;
            len--;
        }
        kunmap(*pagep);
        nidx = node->next;
        if (!nidx) {
            dprint(DBG_BNODE_MOD, "hfs: create new bmap node.\n");
            next_node = hfs_bmap_new_bmap(node, idx);
        } else
            next_node = hfs_bnode_find(tree, nidx);
        hfs_bnode_put(node);
        if (IS_ERR(next_node))
            return next_node;
        node = next_node;

        len = hfs_brec_lenoff(node, 0, &off16);
        off = off16;
        off += node->page_offset;
        pagep = node->page + (off >> PAGE_CACHE_SHIFT);
        data = kmap(*pagep);
        off &= ~PAGE_CACHE_MASK;
    }
}

void hfs_bmap_free(struct hfs_bnode *node)
{
    struct hfs_btree *tree;
    struct page *page;
    u16 off, len;
    u32 nidx;
    u8 *data, byte, m;

    dprint(DBG_BNODE_MOD, "btree_free_node: %u\n", node->this);
    BUG_ON(!node->this);
    tree = node->tree;
    nidx = node->this;
    node = hfs_bnode_find(tree, 0);
    if (IS_ERR(node))
        return;
    len = hfs_brec_lenoff(node, 2, &off);
    while (nidx >= len * 8) {
        u32 i;

        nidx -= len * 8;
        i = node->next;
        hfs_bnode_put(node);
        if (!i) {
            /* panic */;
            printk(KERN_CRIT "hfs: unable to free bnode %u. "
                    "bmap not found!\n",
                node->this);
            return;
        }
        node = hfs_bnode_find(tree, i);
        if (IS_ERR(node))
            return;
        if (node->type != HFS_NODE_MAP) {
            /* panic */;
            printk(KERN_CRIT "hfs: invalid bmap found! "
                    "(%u,%d)\n",
                node->this, node->type);
            hfs_bnode_put(node);
            return;
        }
        len = hfs_brec_lenoff(node, 0, &off);
    }
    off += node->page_offset + nidx / 8;
    page = node->page[off >> PAGE_CACHE_SHIFT];
    data = kmap(page);
    off &= ~PAGE_CACHE_MASK;
    m = 1 << (~nidx & 7);
    byte = data[off];
    if (!(byte & m)) {
        printk(KERN_CRIT "hfs: trying to free free bnode "
                "%u(%d)\n",
            node->this, node->type);
        kunmap(page);
        hfs_bnode_put(node);
        return;
    }
    data[off] = byte & ~m;
    set_page_dirty(page);
    kunmap(page);
    hfs_bnode_put(node);
    tree->free_nodes++;
    mark_inode_dirty(tree->inode);
}